Part A. Field of the Invention
This invention relates to the preparation of ethers by the reaction of polyhydric compounds with olefins in the presence of an acid catalyst. More particularly, it relates to the preparation of mono-ethers of polyhydric compounds by the addition reaction of polyhydric compounds with olefins in the presence of strong acid catalyst. More specifically, it relates to the selective preparation of mono-ethers of polyhydric compounds by reacting a poly-hydric compound with dicyclopentadiene in the presence of a crosslinked acid cation exchange resin.
Part B. Description of the Prior Art
The preparation of mono-ethers of polyhydric compounds by the addition reaction of a polyhydric compound and dicyclopentadiene in the presence of strong acid catalyst is known in the art. Bruson, U.S. Pat. No. 2,393,609 and Bruson and Riener, J. Amer. Chem. Soc., 68, 8 (1946) disclose diol mono-ethers represented by the formula ##STR2## prepared by the addition reaction of a dihydric alcohol with dicyclopentadiene in the presence of a homogeneous strong acid catalyst such as a strong mineral acid catalyst or Lewis acid catalyst. Preparation of diol mono-ethers represented by formula I is problematic because of the lack of selectivity in the addition reaction between the starting diol and dicyclopentadiene. The product distribution, that is, unreacted diol, mono-ether and bis-ether, appears to be governed largely by statistics when the reaction is catalyzed with homogeneous strong acids such as sulfuric acid or boron trifluoride. Optimum yields of mono-ether, I, are obtained only when the addition reaction is carried out in the presence of a large excess, typically, greater than 100 mole percent excess, of diol. The use of excess diol reduces batch productivity and requires lengthened batch times in order to remove unused diol.
The substitution of acid functionalized cation exchange resins, particularly sulfonic acid functionalized resins, for strong mineral acid catalysts and Lewis acid catalysts in a variety of organic chemical reactions is known in the art. R. Kunin, "Ion Exchange Resins," 2d ed., John Wiley & Sons, Inc. New York, NY, 1958 pp. 255-259, discloses catalysis with cation exchange resin in a variety of applications. U.S. Pat. No. 3,037,052 to Bortnick discloses the use of an acid ion exchange resin in the place of conventional soluble strong acid as a catalyst in the esterification of a carboxylic acid with an olefin; the lactonization of a .beta.,.gamma.- or .gamma.,.delta.-unsaturated carboxylic acid; the alkylation of aromatic hydrocarbons and phenols; the condensation of ketones; the polymerization of olefins; and the acylation of olefins and aromatic compounds. Applications of ion exchange catalysis are also discussed in review articles by N. G. Polyanski in Russian Chemical Reviews, 31 (9), 496 (1962); 39 (3), 244 (1970). Further, the phenomenon referred to as "matrix enhancement" , whereby the polymer matrix acts to increase the number of reactant/catalyst contacts over those obtained in homogeneous catalysis at equivalent reactant/catalyst concentrations, has been set forth in an industrial technical publication (A. R. Pitochelli, "Ion Exchange Catalysis and Matrix Effects," Fluid Process Chemicals, Rohm and Haas, 1975). However, the results from the substitution of ion exchange resin catalysts for conventional catalysts, and the achievement of any improvements thereby, are known in the art to be unpredictable.
It has been conceived and demonstrated herein that the problems of the prior art are overcome by this invention wherein the acid catalyst is provided as an acid functionality of a crosslinked cation exchange resin.